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Crystallization and preliminary X-ray diffraction analysis of restriction endonuclease EcoRII
E A Karpova1, E Meehan, M L Pusey
1NASA Marshall Space Flight Center, Huntsville, AL 35812, USA.
Acta Crystallographica. Section D, Biological Crystallography
|September 18, 1999
Summary
Crystallization of restriction endonuclease EcoRII was achieved using ammonium sulfate. The resulting crystals diffract X-rays to 4.0 A resolution, revealing potential pseudo-twofold symmetry for this key enzyme.
Area of Science:
- Structural Biology
- Biochemistry
- Crystallography
Background:
- Restriction endonuclease EcoRII is a key enzyme in DNA manipulation.
- Understanding its structure is crucial for molecular biology applications.
Purpose of the Study:
- To obtain high-quality crystals of restriction endonuclease EcoRII for structural analysis.
- To determine the preliminary crystallographic parameters of EcoRII.
Main Methods:
- Vapor-diffusion technique for protein crystallization.
- X-ray diffraction analysis using a rotating-anode source and imaging-plate detector.
- Space group and unit-cell parameter determination.
Main Results:
- Successful crystallization of EcoRII with ammonium sulfate as the optimal precipitant.
- Obtained crystals diffracting to approximately 4.0 A resolution at 100 K.
- Determined the space group as I23 or I2(1)3 with unit-cell parameters a = b = c = 160.3 A.
- Identified pseudo-twofold symmetry relating two protein molecules in the asymmetric unit.
Conclusions:
- The study successfully established conditions for crystallizing restriction endonuclease EcoRII.
- Preliminary structural data indicate potential dimeric symmetry, guiding further structural investigations.
- Ongoing efforts aim to improve diffraction resolution and identify heavy-atom derivatives for detailed structure determination.